A variety of medical devices are used for chronic, e.g., long-term, delivery of therapy to patients suffering from conditions that range from chronic pain, tremor, Parkinson's disease, and epilepsy, to urinary or fecal incontinence, sexual dysfunction, obesity, spasticity, and gastroparesis. As an example, electrical stimulation generators are used for chronic delivery of electrical stimulation therapies such as cardiac pacing, neurostimulation, muscle stimulation, or the like. Pumps or other fluid delivery devices may be used for chronic delivery of therapeutic agents, such as drugs. Typically, such devices provide therapy continuously or periodically according to parameters contained within a program. A program may comprise respective values for each parameter in a set of therapeutic parameters specified by a clinician.
Chronic implantation of a stimulation generator and one or more leads for delivering stimulation therapy to a patient may be preceded by a trial period. The trial period ordinarily has a prescribed maximum duration, but sometimes is exceeded by the patient or the physician. During the trial period, a clinician evaluates the efficacy of stimulation in alleviating the patient's disorder to determine whether the patient is a good candidate for chronic implantation. The trial period ordinarily involves implantation of a temporary or chronic lead, and percutaneous connection of the lead to an external trial stimulator. Often, connection of the lead to the trial stimulator involves extensive subcutaneous tunneling of the lead to a percutaneous exit site.